Many forms of balers are well known today. The most commonly used field baler of today forms a rectangular bale by picking up crop material by means of a crop pickup, transferring the crop material laterally by means of packer fingers to the forward end of the bale chamber, and then compressing the crop material into a bale by means of a plunger which conventionally operates in the range of 50 to 100 strokes per minute. The bales are then tied off into lengths which generally vary from 3 to 4 feet in length. Most of these bales have a 14 or 16 inch by 18 inch cross section and can be manually handled after baling. Larger bales (16.times.23 inch) are more suitable for machine handling. During the last 40 years large numbers of automatic balers of this type have been produced and hay baled by machines of this type are of good quality and are suitable for long term storage.
During the past 20 years efforts have been made to develop other bale packages which are more suitable for machine handling. One form of baler, pioneered by Vermeer and others, and typically illustrated in U.S. Pat. No. 3,722,197 produces a large round bale of approximately 4 to 5 feet in width and having a similar diameter. Such round bales have good field storage characteristics, but are difficult to handle and are also difficult to stack in enclosed areas. In addition, the baler must be stopped when discharging a bale, and care must be taken when working on a hillside to ensure that the bale does not start rolling down the hill.
An alternate approach to the large round baler is the large rectangular baler of the types shown in U.S. Pats. Nos. 3,552,109 and 4,118,918. To produce large rectangular bales by the conventional baler system, such as used for the smaller 16.times.18 inch bales, a machine must have a relatively heavy structure, and a power train capable of transmitting high torques due to the very high peak loads which occur for a small portion of each cycle when the plunger is completing its stroke. In addition, problems are encountered when tying off such a bale.
In addition to the various commercial types of balers referred to above, other prior art forms of balers have been suggested. One such type is shown in the Molitorisz U.S. Pat. No. 4,175,487. This form of baler utilizes cooperating belts and rollers which are oscillated across the inlet end of the bale chamber.